130 
IOWA ACADEMY OP SCIENCES. 
Trichomes are conspicuous, but only on the superior surface, 
one to three to each bundle. 
Mestome bundles . — There are twelve mestome bundles in a 
leaf, of three types. First, primary type, open both on infer- 
ior and superior surfaces of leaf, i. e., those which have had- 
rome and leptome respectively in contact with stereome, either 
in direct contact or are separated from it by several rows of 
thin-walled parenchyma cells. Second, the secondary type. 
These are entirely surrounded by chlorophyll-bearing paren- 
chyma. Third, intermediate type. These open interiorly. 
Only one bundle of primary type occurs and this is in the carene. 
The leptome and hadrome are in direct contact with each other. 
The leptome is separated from the stereome by thin- walled 
parenchyma cells. Quite a development of thin-walled paren- 
chyma cells occurs above the mestome bundles of carene. Two 
bundles of the third type occur near the margin of leaf. The 
cells separating the leptome from stereome are in this case 
somewhat thicker- wailed than those in carene. 
The mestome bundles of second type are of two sizes, the larg- 
est ones having leptome and hadrome poorly developed, and 
the smallest having no thick- walled cells. 
The thin- walled parenchyma, with its inner closed sheath 
does not differ from that described in Festuca pratensis and 
Lolium perenne. 
Stereome. — This seems to be more strongly developed in this 
species than in Festuca elatior, variety pratensis and Lolium 
perenne. It occurs on the margin of leaf, and also on inferior 
surface of all bundles of first and third types, and on inferior 
surface of all large bundles of secondary type. 
Mesophyll occupies a small area in this species since the mes- 
tome bundles are close together. 
BROMUS PATULUS M. & K. 
(PL ix, Fig. 4; Pi. X, Fig. 7.) 
This was thought to be B. racemosus. 
Epidermis. — The large epidermal cells are thicker- walled than 
in Festuca or Lolium perenne — O ^er the stereome they are 
smaller and thicker-walled. The cuticle is thicker on superior 
than on inferior surface. The leaves are very hairy, and tri- 
chomes occur both on inferior and on superior surface, but are 
more numerous on superior surface. 
